CN111337650B - Multifunctional test device for researching seepage damage mechanism of underground engineering soil body - Google Patents
Multifunctional test device for researching seepage damage mechanism of underground engineering soil body Download PDFInfo
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- CN111337650B CN111337650B CN202010303852.3A CN202010303852A CN111337650B CN 111337650 B CN111337650 B CN 111337650B CN 202010303852 A CN202010303852 A CN 202010303852A CN 111337650 B CN111337650 B CN 111337650B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/24—Earth materials
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D33/00—Testing foundations or foundation structures
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/02—Investigating particle size or size distribution
- G01N15/0205—Investigating particle size or size distribution by optical means, e.g. by light scattering, diffraction, holography or imaging
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/10—Investigating individual particles
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
- G01N3/10—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces generated by pneumatic or hydraulic pressure
- G01N3/12—Pressure testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0001—Type of application of the stress
- G01N2203/0003—Steady
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0014—Type of force applied
- G01N2203/0016—Tensile or compressive
- G01N2203/0019—Compressive
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/003—Generation of the force
- G01N2203/0042—Pneumatic or hydraulic means
- G01N2203/0044—Pneumatic means
Abstract
The invention discloses a multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body, and relates to the technical field of seepage test equipment, comprising a main box body, a loading system, a pipeline simulation system, an adjusting system, a foundation pit supporting mechanism, a measuring system and a testing system; the main box body is used for bearing soil, the loading system is used for applying load to the soil, the pipeline simulation system is used for simulating a pipe-jacking pipeline, the adjusting system is used for supplying water into the soil and controlling water pressure, the foundation pit supporting mechanism is used for simulating foundation pit supporting, the measuring system is used for detecting pressure in the loading system and observing movement and change conditions of the soil, and the measuring system is used for measuring particle size and quantity of flowing sand. The model device is used for simulating the deformation of the soil body under the action of the underground water, the change condition of pore water pressure and the like, and further can better solve foundation pit damage caused by underground water seepage.
Description
Technical Field
The invention relates to the technical field of seepage test equipment, in particular to a multifunctional test device for researching a seepage damage mechanism of a soil body of an underground engineering.
Background
The coastal city construction development is rapid, the number of deep foundation pits is increased, foundation pits which are closer to the sea are particularly rich in groundwater resources, and groundwater and seawater are hydraulically connected to a certain degree. The groundwater problem of the foundation pit facing the sea is more complicated than that of a common foundation pit, such as the occurrence of sudden surges at the bottom of the foundation pit and the possibility of piping is higher. The pipe jacking is applied to non-excavation laying of urban underground water supply and drainage pipelines in coastal economically developed areas, a pipe jacking pit is a small square foundation pit, and during the use of the pipe jacking, under the condition of higher underground water level, the interaction of the initial leakage of the pipeline and soil disturbance causes local erosion of the pipeline. The groundwater carries fine sand to infiltrate into the pipeline from the damaged mouth, thereby causing the loss of peripheral backfill sand particles. In the foundation pit accidents, the accident caused by improper treatment of the underground water accounts for 22%, so that the underground water is one of important influencing factors for the foundation pit accidents. Under the condition of complex geology in the sea, the sudden gushing, piping and pipeline leakage have typical and research value relative to other foundation pit accidents, and play a certain role in reference and guidance for the foundation pit excavation treatment.
Most of the existing indoor tests are biased to singly researching remedial measures after certain groundwater seepage problems (piping, surging and pipeline leakage) occur, few researches on piping, surging and pipeline leakage occur before and during the occurrence process are carried out, and in order to radically cure engineering damage caused by groundwater, most importantly, the deformation state of soil before damage is analyzed. The novel device can simulate the states of foundation pit excavation and pipeline leakage under the groundwater condition, not only can test the motion state of the soil body at each moment, but also can research the stress state of the soil body before piping, gushing and pipeline leakage damage, is more in line with the actual engineering requirement, and can meet the test requirement of accurately measuring the soil body flow state, pore water pressure and the like under the simulated real groundwater state.
Aiming at groundwater seepage, especially piping caused by seepage water and foundation pit surge and pipeline seepage accidents caused by pressure-bearing water, the invention can solve the problem of predicting the development trend of foundation pit and pipeline damage under the action of groundwater seepage, can also prevent and treat the problem of foundation pit and pipeline damage caused by groundwater seepage, can provide reference for foundation pit dewatering, and can be used for guiding the treatment of related accidents.
In summary, although such accidents are often reported, damage precursors and process researches for piping, foundation pit surges, and local erosion problems of pipelines caused by seepage under the action of groundwater are less common. So that the problems of piping and foundation pit surge damage and local erosion of the pipeline under the action of groundwater seepage are simulated through an indoor model test. On the basis of theoretical analysis of test results, a judging method of piping and foundation pit surge is quantitatively provided, and the pipeline leakage mechanism has higher theoretical significance and important engineering application value.
Disclosure of Invention
In order to solve the technical problems, the invention provides a multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body, which is used for simulating the deformation of the soil body under the action of underground water and the change condition of pore water pressure, so that foundation pit damage caused by underground water seepage can be better solved.
In order to achieve the above object, the present invention provides the following solutions:
the invention provides a multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body, which comprises a main box body, a loading system, a pipeline simulation system, an adjusting system, a foundation pit supporting mechanism, a measuring system and a testing system, wherein the main box body is connected with the loading system; the main box body is used for bearing soil, the loading system is used for applying load to the soil, the pipeline simulation system is used for simulating a pipe-jacking pipeline, the adjusting system is used for supplying water into the soil and controlling water pressure, the foundation pit supporting mechanism is used for simulating foundation pit supporting, the measuring system is used for detecting pressure in the loading system and observing movement and change conditions of the soil, and the measuring system is used for testing grain size and quantity of flowing sand.
Optionally, toughened glass is arranged on the front side of the main box body, a plurality of pressure guide holes are formed in the rear side of the main box body, a plurality of first water through valves are arranged on the rear side of the main box body close to the bottom, a soil retaining unit is arranged on the rear side of the main box body close to the middle, a plurality of water through valves are arranged on the left side of the main box body from top to bottom, a first pipeline opening is formed in the lower portion of the left side of the main box body, a plurality of sand outlets are formed in the right side of the main box body from top to bottom, a second pipeline opening is formed in the lower portion of the right side of the main box body, the first pipeline opening and the second pipeline opening are coaxially arranged, a cleaning opening is further formed in the lower portion of the right side of the main box body, and a plurality of holes are formed in the top surface of the main box body; the first pipeline opening, the second pipeline opening, the cleaning opening, the sand outlets and the holes are respectively plugged by flanges;
the main box body is characterized in that the loading system is arranged at the inner top of the main box body, the pipeline simulation system is arranged at the first pipeline opening and the second pipeline opening, the adjusting system is communicated with the water through valves, and the foundation pit supporting mechanism is arranged in the main box body.
Optionally, governing system includes regulation air compressor machine, adjusts air-vent valve, water tank, manometer and multiport valve, the gas outlet of regulation air compressor machine with the water tank is linked together, adjust the air-vent valve set up in adjust the air compressor machine with between the water tank, the delivery port of water tank bottom with the multiport valve is linked together, the manometer set up in the water tank with between the multiport valve, a plurality of exports of multiport valve all with the main tank is linked together.
Optionally, the loading system comprises a loading air compressor, a loading pressure regulating valve and an air bag; the air bag is arranged at the top in the main box body, and the loading pressure regulating valve is arranged between the air inlet of the air bag and the air outlet of the loading air compressor.
Optionally, the pipeline simulation system comprises an inner layer pipe and an outer layer pipe which are coaxially arranged, wherein one end of the inner layer pipe is open, the other end of the inner layer pipe is closed, and the length of the inner layer pipe is longer than that of the outer layer pipe; the inner layer pipe wall is provided with a plurality of first damaged openings, the outer layer pipe wall is provided with three second damaged openings, and the positions of the first damaged openings correspond to the positions of the second damaged openings.
Optionally, the foundation pit supporting mechanism includes two retaining plates and a plurality of bracing pieces, two retaining plates place in middle part in the main tank body, just have first interval between two retaining plates, a plurality of bracing pieces set up in between two retaining plates.
Optionally, the bracing piece includes loop bar and two telescopic links, the one end activity of two telescopic links set up in the loop bar, the other end of two telescopic links with two retaining plates are connected.
Optionally, the measurement system includes a plurality of pore pressure meters, communication interface and calculation module, a plurality of pore pressure meters set up in on the main tank body, a plurality of pore pressure meters pass through communication interface with calculation module electricity is connected.
Optionally, the test system includes a sampling bottle, a laser particle analyzer and a particle counter, the sampling bottle is used for sampling liquid and solid flowing out of the main box, the laser particle analyzer is used for measuring particle size distribution of the samples, and the particle counter measures the number of sampled particles.
Compared with the prior art, the invention has the following technical effects:
1. the test main box body can provide three seepage modes which can meet the requirements of piping, sudden surge and local erosion of pipelines to cause sand leakage, the test device can enable the main box body to meet the effect of simulating various groundwater modes, seepage simulation under different pressure-bearing water directions of the bottom and the side surfaces can be realized, and the main box body can be utilized to the greatest extent.
2. The loading system of the invention utilizes the air compressor to inflate the air bag, and applies uniform pressure to the soil sample to simulate the load of the overlying house. The method can realize the purpose of applying uniform vertical pressure by using a simple device.
3. According to the invention, the pressure output from the air compressor is regulated by the pressure reducing valve and then is led into the water tank, and the water pressure in the water pipe at the bottom of the water tank is regulated by the other pressure reducing valve and then is connected with the corresponding water-through valve. The pressure-bearing water head regulating system can simulate stable underground water flow pressures with different magnitudes.
4. The pressure-bearing overhead layer arranged at the bottom of the invention consists of a stainless steel plate with a water through hole and short columns arranged at the lower part at intervals. The method can realize full saturation of the test soil in the main box body from bottom to top, and can lead water flow to uniformly flow through the soil.
5. The pipeline simulation system adopts the double-layer pipe, so that the sand leakage condition before the test is not started can be prevented, the inner-layer pipe which can flexibly rotate can play the roles of controlling the sand leakage condition and containing the sand leakage, and the sand leakage condition can be easily taken out after the test is ended. Therefore, the sand leakage caused by the local erosion of the pipeline can be better observed and tested.
6. The pore pressure measuring system at the back of the main box body is used for testing pore water pressures at different positions, and can be used for realizing the requirements of observing the spatial distribution of the pore water pressures in the soil sample and testing the time evolution characteristics.
7. The detachable soil retaining unit is used for temporarily retaining the non-excavated soil body of the passive area of the foundation pit, and can be removed layer by layer before each layer of soil body is excavated, and then the soil is excavated by a shovel matched with the size of the foundation pit. Compared with the traditional method for directly excavating and taking out soil downwards, the method can definitely excavate the soil layer of each layer without affecting the non-excavation, is convenient to operate, and reduces the workload of excavating and unloading the soil of the foundation pit.
8. The method can accurately simulate the bracing process in the foundation pit excavation process, the inner support cannot have disturbance influence on the non-excavated soil body of the foundation pit in the installation process, the inner support is fixedly connected with the retaining wall through the support rods, and compared with the method for directly propping the retaining wall by the inner support in the traditional test to realize bracing, the bracing condition in the actual foundation pit engineering excavation process can be reflected objectively.
9. In order to deeply analyze the characteristics of the flowing sand, the invention adopts the laser particle size meter to measure the particle size of the flowing sand, and then uses the particle counter to test the quantity of sand grains, so that the measured result is accurate and reliable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a front view of the main housing;
FIG. 2 is a rear view of the main housing;
FIG. 3 is a top view of the main housing;
FIG. 4 is a left side view of the main housing;
FIG. 5 is a right side view of the main housing;
FIG. 6 is a diagram of an underground water seepage model test device;
FIG. 7 is a diagram of a foundation pit surge model test device;
FIG. 8 is a pipe leak test apparatus diagram;
FIG. 9 is a schematic diagram of a pipeline modeling system.
Reference numerals illustrate: 1. a sand outlet; 2. a second pipeline opening; 3. calibrating a point by a particle image velocimetry; 4. a second water-passing valve; 5. a pressure guiding hole; 6. an opening; 7. a soil blocking unit; 8. a first pipeline opening; 9. cleaning the mouth; 10. sampling bottle; 11. a particle image velocimetry system; 12. a soil retaining plate; 13. a pipeline simulation system;
100. a main case; 200. an adjustment system; 300. loading a system; 400. a measurement system;
201. adjusting an air compressor; 202. regulating a pressure regulating valve; 203. a water tank; 204. a pressure gauge; 205. a multi-way valve;
301. loading an air compressor; 302. loading a pressure regulating valve; 303. an air bag;
131. an inner layer tube; 132. an outer layer tube.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Embodiment one:
as shown in fig. 1, the embodiment provides a multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body, which comprises a main box body 100, a loading system 300, a pipeline simulation system 13, an adjusting system 200, a foundation pit supporting mechanism, a measuring system 400 and a test system; the main box 100 is used for bearing soil, the loading system 300 is used for applying load to the soil, the pipeline simulation system 13 is used for supplying water into the soil to simulate groundwater seepage, the adjusting system 200 is used for supplying water into the soil and controlling water pressure, the foundation pit supporting mechanism is used for simulating foundation pit supporting, the measuring system 400 is used for detecting pressure in the loading system 300 and observing movement and change conditions of the soil, and the measuring system 400 is used for testing grain size and quantity of flowing sand.
In this embodiment, as shown in fig. 1-9, the front side of the main box 100 is provided with toughened glass, the rear side of the main box 100 is provided with a plurality of pressure guiding holes 5, the rear side of the main box 100 is close to the bottom and is provided with five first water through valves, the rear side of the main box 100 is close to the middle and is provided with a soil retaining unit 7, the left side of the main box 100 is provided with four second water through valves 4 from top to bottom, the lower part of the left side of the main box 100 is provided with a first pipeline mouth 8, the right side of the main box 100 is provided with three sand outlets 1 from top to bottom, the lower part of the right side of the main box 100 is provided with a second pipeline mouth 2, the first pipeline mouth 8 and the second pipeline mouth 2 are coaxially arranged, the lower part of the right side of the main box 100 is also provided with a cleaning mouth 9, and the top of the main box 100 is provided with three holes 6; the first pipeline opening 8, the second pipeline opening 2, the cleaning opening 9, the three sand outlets 1 and the three holes 6 are respectively plugged by flanges; the cleaning port 9 is a rectangular port.
The top is provided with in the main tank body 100 loading system 300, pipeline analog system 13 set up in first pipeline mouth 8 with second pipeline mouth 2 department, governing system 200 with four second water valve 4 all communicate, foundation ditch supporting mechanism set up in the main tank body 100 is inside.
The whole structure of the main box body 100 is cuboid, the size of the inner space is 1100mm x 300mm x 650mm, and the wall thickness of the structure is 20mm. The bottom of the main box frame is fixed on a main box bottom plate, and a pressure-bearing overhead layer consisting of a stainless steel plate with a water through hole, a short column and a reverse filtering geotextile is arranged at a position 70mm away from the bottom. The toughened glass with the front side surface being 20mm thick is fixed on the main box base through spot welding around, the top is connected by a stainless steel top plate through four-sided bolts, the top plate is uniformly provided with three holes 6 with the diameter of 50mm along the long side direction at the center line position, and the three holes are used for placing the air bags 303 during loading, then introducing the gas pipe and covering the pipes with flanges at other times. The back plate is perforated from top to bottom and from left to right at intervals of 150mm, 52 holes are drilled in total, and each pressure guiding hole 5 is connected with a hole pressure gauge. The middle part of the backboard is provided with 7 detachable stainless steel bars serving as a soil retaining unit 7, the width of the soil retaining unit is 300mm, the height of the soil retaining unit is 50mm, and the soil retaining unit is fixed on a main box frame through screwing and fastening of bolts. The stainless steel strips are connected in a meshed mode like mortise and tenon, and in order to achieve a good waterproof effect, water-stopping rubber strips are placed between the stainless steel strips, and glass cement is sprayed to prevent water leakage. Four second water-passing valves 4 are uniformly distributed on the left side along the height direction at the center line position, the bottom is close to the glass position and provided with a pipeline opening with the diameter of 50mm, and a stainless steel plate with a water-passing hole is arranged at the position 100mm away from the left side plate. Three sand outlets 1 with the diameter of 50mm on the right side are arranged at the center line position, and the distances from the bottoms are 450mm, 300mm and 150mm respectively. The bottom is provided with a pipeline opening corresponding to the left side near the glass position for placing the pipeline simulation system 13. The right side pressure-bearing overhead layer height position is provided with a rectangular sand outlet 1 for cleaning sand left on the overhead layer after the test is finished.
The regulating system 200 comprises a regulating air compressor 201, a regulating pressure regulating valve 202, a water tank 203, a pressure gauge 204 and a multi-way valve 205, wherein an air outlet of the regulating air compressor 201 is communicated with the water tank 203, the regulating pressure regulating valve 202 is arranged between the regulating air compressor 201 and the water tank 203, a water outlet at the bottom of the water tank 203 is communicated with the multi-way valve 205, the pressure gauge 204 is arranged between the water tank 203 and the multi-way valve 205, and a plurality of outlets of the multi-way valve 205 are all communicated with the main box 100.
The loading system 300 comprises a loading air compressor 301, a loading pressure regulating valve 302 and a gas cylinder 303; the air bag 303 is disposed at the top of the main casing 100, and the load pressure regulating valve 302 is disposed between the air inlet of the air bag 303 and the air outlet of the load air compressor 301. The air bag 303 is attached to the inner wall of the main box 100 to simulate the load of an overlying house, and after the loading air compressor 301 is inflated, the air bag 303 applies uniform load to the surface of the soil body.
The pipeline simulation system 13 comprises an inner layer pipe 131 and an outer layer pipe 132 which are coaxially arranged, wherein one end of the inner layer pipe 131 is open, the other end of the inner layer pipe is closed, and the length of the inner layer pipe 131 is longer than that of the outer layer pipe 132; three first breakage openings are formed in the wall of the inner tube 131, and three second breakage openings are formed in the wall of the outer tube 132 along the same straight line. The positions of the three first breakage openings correspond to the positions of the second breakage openings.
The inner tube 131 and the outer tube 132 are both PVC tubes. The diameter of the outer tube 132 was 50mm, and three breakage openings having a diameter of 3mm were distributed on the surface. The inner tube 131 has a diameter slightly smaller than that of the outer tube 132, and is closely attached to the inner wall of the outer tube 132, and breakage openings having a diameter of 5mm are distributed at positions corresponding to breakage openings of the outer tube 132.
The foundation pit supporting mechanism comprises two retaining plates 12 and seven supporting rods, the two retaining plates 12 are arranged in the middle of the main box body 100, a first interval is reserved between the two retaining plates 12, and the seven supporting rods are arranged between the two retaining plates 12.
The retaining plate 12 is an aluminum plate of a size 300mm x 440mm x 4mm.
The supporting rod comprises a loop bar and two telescopic bars, one ends of the two telescopic bars are movably arranged in the loop bar, and the other ends of the two telescopic bars are connected with the two retaining plates 12.
The measurement system 400 includes a plurality of pore pressure gauges, a communication interface, and a calculation module, where the pore pressure gauges are disposed on the main box 100, and the pore pressure gauges are electrically connected with the calculation module through the communication interface. A plurality of pore pressure gauges are provided in the plurality of pressure guide holes 5.
The test system comprises a sampling bottle 10, a laser particle size analyzer and a particle counter, wherein the sampling bottle 10 is used for sampling liquid and solid flowing out of the main box body 100, the laser particle size analyzer is used for measuring particle size distribution of the samples, and the particle counter is used for measuring the particle number of the samples.
The specific operation mode of the test is as follows:
1. groundwater seepage model test
As shown in fig. 6.
1. Preparation and placement of sand samples: the stainless steel plate is locked on the stainless steel plate with the water through hole at the bottom by bolts, and sand bodies with a certain grading (adopting sand with two particle size ranges of 5-10mm and 0.5-1mm respectively, and the mass ratio of the two sand is 9:2) are placed into a main box body 100 for compacting and saturating sand samples.
2. House load is applied: after the top plate of the main box body 100 is covered, three holes 6 at the top are opened, the three holes extend into a pipe connecting the loading air compressor 301 and the air bag 303, and after the loading air compressor 301 is inflated, uniform load is applied to the surface of the soil sample by means of the pressure in the air bag 303 to simulate the load of an overlying house. The pressure output by the loading air compressor 301 is regulated through the pressure reducing valve to simulate the load of 6 floors of houses, and the pressure output by the loading air compressor 301 is 0-90kPa.
3. And (3) introducing pressure-bearing water: after removing bubbles, connecting all water pipes, opening an adjusting air compressor 201, adjusting the pressure to the required pressure by adjusting a pressure regulating valve 202, injecting the pressure into a water tank 203 after the pressure is stabilized, accessing the pressure water into a digital pressure gauge 204 through a water pipe at the bottom of the water tank 203, accurately adjusting the pressure again, then introducing four second water-passing valves 4 at the left side, and sequentially opening three flanges covered by a sand outlet 1 at the right side. The water flow passes through the stainless steel plate with the water holes on the left side and flows through the saturated sand body to simulate a horizontal seepage mode. Five water flows with different pressures of 20kPa, 30kPa, 40kPa, 50kPa and 60kPa are introduced to flush the sand body out of the sand outlet 1 on the right side. Samples were taken at intervals at the sand outlet 1 with a sampling bottle 10, and then the particle size and the amount of the sand flowing out were measured by a test system.
4. In the test process, the movement and deformation of the sand body during horizontal seepage are measured by the particle image velocimetry monitoring system, the position change of the sand body at any moment is obtained, and the characteristic that the pore water pressure of the soil sample changes along with the spatial distribution and time is measured by the measuring system 400.
2. Foundation pit surging model test
As shown in fig. 7.
1. Preparing and placing a soil sample: the stainless steel plate was bolted to the stainless steel plate with the water holes at the bottom, and standard sand of 70mm thickness was placed at the bottom of the main tank 100. And when the sand body is paved to be 20mm thick, the sand body is compacted by manual pressure, and water is slowly poured. Residual soil with the water content of 27% is paved on the sand layer in layers with the thickness of 280mm, and each layer is compacted by manual force.
2. Placing a supporting structure: two aluminum retaining plates 12 are placed at 110mm from the bottom of the main casing 100 at the position of the excavation of the vertically attached foundation pit.
3. Applying horizontal pressure to the bearing water: the first water passing valve at the bottom is closed, the four second water passing valves 4 at the left side are opened, and water flows through the stainless steel plate with the water passing holes at the left side to simulate a horizontal gushing water flow mode. The air pressure generated by the air compressor 201 is converted into water pressure and then transmitted to a standard sand aquifer, and the pressure of the bearing water head is kept at a constant value of 40 kPa.
4. Excavation of a foundation pit: then, photographing was performed at 5 minute intervals by a camera provided in front of the tempered glass. In the test process, the symmetrical surface soil retaining unit 7 is removed and soil in the main box body 100 is excavated when the pressure of each stage of pressure-bearing water head is kept to be a constant value by adjusting the valve and the pressure gauge 204, the first support is installed when the soil is excavated below the designed position of the first support, the excavation thickness is changed to be 30mm,45mm,60mm,75mm,90mm and the like in sequence, and the supports are installed by adopting the same method until the sudden surge damage occurs. Pore pressure gauges required by the test are uniformly arranged at the positions of the pressure guide holes 5 reserved in the back plate, and pore water pressure monitoring in soil is carried out. And acquiring and recording the reading of the micro pore water pressure sensor in the initial test state by using a data acquisition instrument, shooting a test soil body photo in the initial test state by using a digital camera, and then analyzing.
In the underground water seepage model test and the foundation pit surge model test, if vertical pressure-bearing water seepage is simulated, a stainless steel plate is required to be placed on the stainless steel plate with the water through holes on the left side in the sand sample placing process, and filter cloth is paved on the upper surface of the stainless steel bearing plate with the water through holes on the bottom, so that the soil body is prevented from being lost in the water level change process. When the water is injected, the pressure water is connected into the digital pressure gauge 204 through the water pipe at the bottom of the water tank 203, and then is introduced into the five water-through valves at the bottom after the pressure is accurately regulated again, and other test steps are the same as those of the two tests.
3. Pipeline leakage test
As shown in fig. 8.
1. Preparation and placement of sand samples: the stainless steel plate is placed on the stainless steel plate with the left water through hole, and the filter cloth is paved on the upper surface of the stainless steel bearing plate with the bottom water through hole, so that the soil body is prevented from being lost in the water level change process. The outer tube 132 with the closed end facing right is placed into the bottom reserved tube port, and the broken port is kept upward. Then, the inner tube 131 was put in the same manner, and the breakage opening was oriented in the direction of the observation glass. After the relative positions of the inner and outer layers 132 are adjusted, the sand body with a certain grading is put into the main box body 100 to be pressed tightly, so that a sand sample is saturated.
2. Applying water pressure: after the main box body 100 is covered with a top plate, three third water through valves arranged at three holes 6 at the top are installed, and after bubbles are removed, all water pipes are connected. After the start of the test, the inner tube 131 was rotated to correspond the positions of the breakage openings of the inner tube 131 and the outer tube 132. The air compressor 201 is opened, the pressure gauge 204 is used for adjusting the pressure to the required stable pressure, then the pressure water is injected into the water tank 203, the pressure water is connected into the digital pressure gauge 204 through a water pipe at the bottom of the water tank 203, the pressure is accurately adjusted again, then the pressure water is introduced into three third water through valves at the top, and then the pressure water in the vertical direction flows through the saturated sand body from top to bottom.
3. In the test process, the movement and deformation of the sand body during horizontal seepage are measured by a particle image velocimetry monitoring system, so that the position change of the sand body at any moment is obtained, and the spatial distribution and the evolution characteristic along with time of the pore water pressure of the soil sample are measured by a pore pressure measuring system.
4. At the end of the test, the inner tube 131 containing the leaked sand was taken out, and then the particle size and the amount of the leaked sand were measured by a test system.
It should be noted that it will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
The principles and embodiments of the present invention have been described in this specification with reference to specific examples, the description of which is only for the purpose of aiding in understanding the method of the present invention and its core ideas; also, it is within the scope of the present invention to be modified by those of ordinary skill in the art in light of the present teachings. In view of the foregoing, this description should not be construed as limiting the invention.
Claims (5)
1. The multifunctional test device for researching the seepage damage mechanism of the soil body of the underground engineering is characterized by comprising a main box body, a loading system, a pipeline simulation system, an adjusting system, a foundation pit supporting mechanism, a measuring system and a testing system; the main box body is used for bearing soil, the loading system is used for applying load to the soil, the pipeline simulation system is used for simulating a pipe-jacking pipeline, the adjusting system is used for supplying water into the soil and controlling water pressure, the foundation pit supporting mechanism is used for simulating foundation pit supporting, the measuring system is used for detecting pressure in the loading system and observing movement and change conditions of the soil, and the measuring system is used for testing grain size and quantity of flowing sand;
the toughened glass is arranged on the front side surface of the main box body, a plurality of pressure guide holes are formed in the rear side surface of the main box body, a plurality of first water through valves are arranged at positions, close to the bottom, of the rear side surface of the main box body, a soil retaining unit is arranged at positions, close to the middle, of the rear side surface of the main box body, a plurality of water through valves are arranged on the left side surface of the main box body from top to bottom, a first pipeline opening is formed in the lower portion of the left side surface of the main box body, a plurality of sand outlets are formed in the right side surface of the main box body from top to bottom, a second pipeline opening is formed in the lower portion of the right side surface of the main box body, the first pipeline opening and the second pipeline opening are coaxially arranged, a cleaning opening is further formed in the lower portion of the right side surface of the main box body, and a plurality of holes are formed in the top surface of the main box body; the first pipeline opening, the second pipeline opening, the cleaning opening, the sand outlets and the holes are respectively plugged by flanges;
the loading system is arranged at the inner top of the main box body, the pipeline simulation system is arranged at the first pipeline opening and the second pipeline opening, the adjusting system is communicated with the water through valves, and the foundation pit supporting mechanism is arranged in the main box body;
the regulating system comprises a regulating air compressor, a regulating pressure regulating valve, a water tank, a pressure gauge and a multi-way valve, wherein an air outlet of the regulating air compressor is communicated with the water tank, the regulating pressure regulating valve is arranged between the regulating air compressor and the water tank, a water outlet at the bottom of the water tank is communicated with the multi-way valve, the pressure gauge is arranged between the water tank and the multi-way valve, and a plurality of outlets of the multi-way valve are all communicated with the main tank;
the loading system comprises a loading air compressor, a loading pressure regulating valve and an air bag; the air bag is arranged at the top in the main box body, and the loading pressure regulating valve is arranged between the air inlet of the air bag and the air outlet of the loading air compressor;
the pipeline simulation system comprises an inner layer pipe and an outer layer pipe which are coaxially arranged, wherein one end of the inner layer pipe is open, the other end of the inner layer pipe is closed, and the length of the inner layer pipe is longer than that of the outer layer pipe; the inner layer pipe wall is provided with a plurality of first damaged openings, the outer layer pipe wall is provided with three second damaged openings, and the positions of the first damaged openings correspond to the positions of the second damaged openings.
2. The multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body according to claim 1, wherein the foundation pit supporting mechanism comprises two retaining plates and a plurality of supporting rods, the two retaining plates are arranged in the middle part in the main box body, a first interval is arranged between the two retaining plates, and the plurality of supporting rods are arranged between the two retaining plates.
3. The multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body according to claim 2, wherein the supporting rod comprises a sleeve rod and two telescopic rods, one ends of the two telescopic rods are movably arranged in the sleeve rod, and the other ends of the two telescopic rods are connected with the two retaining plates.
4. The multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body according to claim 1, wherein the measuring system comprises a plurality of pore pressure meters, a communication interface and a calculation module, the pore pressure meters are arranged on the main box body, and the pore pressure meters are electrically connected with the calculation module through the communication interface.
5. The multifunctional test device for researching a seepage damage mechanism of an underground engineering soil body according to claim 1, wherein the test system comprises a sampling bottle, a laser particle size analyzer and a particle counter, the sampling bottle is used for sampling liquid and solid flowing out of the main box body, the laser particle size analyzer is used for measuring particle size distribution of the sampling, and the particle counter is used for measuring the number of sampling particles.
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| CN112578101B (en) * | 2020-12-03 | 2021-10-01 | 中国地质大学（武汉） | Model test device for ground collapse caused by pipeline leakage |
| CN112730163B (en) * | 2020-12-24 | 2022-09-27 | 昆明理工大学 | Method for observing movement locus of particles in bulk |
| CN113790699B (en) * | 2021-07-28 | 2023-12-05 | 浙江工业大学 | Soil retaining fixing device and horizontal displacement measurement test device with different depths |
| CN114232558B (en) * | 2021-12-30 | 2022-06-28 | 中国有色金属工业昆明勘察设计研究院有限公司 | Dam piping simulated destruction observation device and use method thereof |
| CN114582219B (en) * | 2022-02-23 | 2023-08-11 | 山东高速工程建设集团有限公司 | Foundation pit adjacent building construction simulation device |
| CN115266725B (en) * | 2022-06-23 | 2023-08-25 | 北京科技大学 | Test device and test method for collapse caused by leakage of buried pipeline |
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